ABSTRACT
As part of the safety assessment of the Channel Tunnel, the cut and cover section running between Castle Hill and Holywell on the English side was assessed under a seismic loading. Seismic inertial loads on the structure were applied as quasi-static loads in the transverse direction with seismic soil pressures being determined from a consideration of compatibility requirements between the ground and structural displacements. In the longitudinal direction strains and corresponding loads were estimated using wave propagation theory. In the vertical direction inertial loads were applied in a quasi-static manner allowing for dynamic interaction between the tunnel roof and overburden. Liquefaction of the ground was also considered and shown not be a problem. The assessment demonstrated that the various structural forms investigated had adequate capacity to resist loading from a seismic event with a 0.2g peak horizontal ground acceleration with additional margins beyond that of at least 40% before collapse.
